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Articles 1 - 6 of 6
Full-Text Articles in Ecology and Evolutionary Biology
Effects Of Variable And Changing Environments On Demography: Inferences From A Lesser Snow Goose Colony, David T. Iles
Effects Of Variable And Changing Environments On Demography: Inferences From A Lesser Snow Goose Colony, David T. Iles
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The mean and variability of environmental conditions have changed as a result of human activity, and continued changes are predicted. The strongest effects on natural populations will often be channeled through species interactions, as shifts in species range limits and life cycle schedules will shift in relation to each other. These changes will often impact rates of survival, growth, and reproduction simultaneously, and these effects will likely differ across habitats.
In chapter 2, I used mathematical modeling and computer simulations to investigate the evolutionary significance of increasingly variable environments, and examine how evolutionary pressures change when multiple vital rates are …
Ecology Of Treeline Whitebark Pine (Pinus Albicaulis) Populations In Central Idaho: Successional Status, Recruitment, And Mortality, And A Spring Temperature Reconstruction From Whitebark Pine Tree Rings, Dana Lee Perkins
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
This research investigated the successional status of treeline whitebark pine (Pinus albicaulis) populations on 14 stands in central Idaho and used empirical statistical models to determine the principal factors affecting recruitment and mortality. The longest lived whitebark pines from four additional high-elevation sites were used to develop a tree-ring chronology to reconstruct over 1,000 years of average April-May temperature.
The assessment of stand structures using size-frequency distributions generally provides evidence that treeline whitebark pine populations are currently self-sustaining in areas of low to nonexistent incidence of white pine blister rust (Cronartium ribicola). However the presence of …
The Effects Of Disease, Prey Fluctuation, And Clear-Cutting On American Marten In Newfoundland, Canada, Richard J. Fredrickson
The Effects Of Disease, Prey Fluctuation, And Clear-Cutting On American Marten In Newfoundland, Canada, Richard J. Fredrickson
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Individual variation in survival and behavior of American marten (Martes americana) was studied in relation to disease, prey fluctuation, and clear-cutting from 10 January 1986 through 20 August 1987 in Newfoundland, Canada. Thirty-seven of forty marten captured on the study area were telemetered and monitored for part or all of the study.
Marten mortality was concentrated in two intervals, fall 1986 and late winter 1987. Mortality during fall 1986 was attributable to encephalitis, while marten deaths during late winter 1987 resulted from predation and starvation attributable to the prey decline. Nonsuppurative encephalitis was first detected 7 October 1986; …
The Interaction Of Ultraviolet-B Radiation Stress And Plant Competition In Agricultural Plant Populations, Warren Glenn Gold
The Interaction Of Ultraviolet-B Radiation Stress And Plant Competition In Agricultural Plant Populations, Warren Glenn Gold
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The effect of ultraviolet-B radiation enhancement upon the competitive interactions of two species pairs was studied in the field. Wheat (Triticum aestivum L. 'Bannock') was paired with wild oat (Avena fatua L.) and jointed goatgrass (Aegilops cylindrica Host) to represent competition between species pairs in agricultural situations. Specially modulated ultraviolet lamp systems provided either low ultraviolet-B enhancement (simulation of a 16 % ozone layer reduction based upon the generalized plant action spectrum), high ultraviolet-B enhancement (40 % ozone reduction) or control (ambient solar ultraviolet-B) irradiance.
Ultraviolet-B radiation enhancement significantly altered the competitive interactions of the species pairs. …
Reproduction And Hematology Of The Cache Elk Herd, Thomas B. Follis
Reproduction And Hematology Of The Cache Elk Herd, Thomas B. Follis
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The initial three years of a 10-year reproductive study of elk involved three major phases. A fourth was added because of convenience. Objective 1 was to ascertain pregnancy rates in yearling and mature elk by rectal palpation, associate these rates with subsequent fall cow/calf ratios, and to test concurrently an ultrasonic fetal heart detector. Rectally observed anatomical changes in gravid uteri of cattle were directly applicable to elk. Ultrasonic detections of pregnancies in elk and deer were unsuccessful.
Pregnancy rates in the 1969-70 winter of 100 and 0 percent, respectively, for 19 adult and five yearling elk were associated with …
Population Ecology Of Uinta Ground Squirrels, Norman A. Slade
Population Ecology Of Uinta Ground Squirrels, Norman A. Slade
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
The behavior and ecology of Uinta ground squirrels (Spermophilus armatus) at the Utah State University Forestry Field Station northeast of Logan, Utah were studied from 1964-1971 to determine the role of behavior in population regulation. From 1965 to 1968, data were collected to establish population norms. In 1968, the population density was reduced experimentally to help elucidate regulatory processes. This paper compares the dynamics of the population before and after the population reduction.
Before the density reduction, juvenile survival was lower than that of yearlings and adults. The disappearance of juveniles was associated with their tendency to disperse …